Here line of sight to Crystal Palace, I normally get very good tv reception
with a wide band loft aerial. I fear it might well be time, once again to
change its coax or get a decent aerial fro Freeview. T multiplex which has
channels 20 21 and some others on it is coming up no signal all of a
sudden, unlike the others. Is this one particularly weak or very high in the
band at this site. Its been fine for years, so unless its on reduced power,
I guess its more expense. sigh.
Brian

PS I just tried the discone from my radio scanner on the TV, and get all
the channels no problems, so I guess that is rather an obvious pointer that
I have an aerial with built in attenuator all of a sudden. Last time it
looked like something had eaten the pvc out of the coax. What is the best
stuff these days? Maybe one that wildlife won't eat?
grin

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Brian Gaff wrote:

> multiplex which has channels 20 21 and some others on it is coming up no
> signal all of a sudden, unlike the others. Is this one particularly weak or
> very high in the band at this site.
Sounds like you mean the SDN/COM4 mux which has LCNs 20 drama and 21 5USA

That's on UHF E25, i.e. there are other muxes higher and lower frequencies than it

It's a 200 kW mux like most of the others, except local TV and COM7 which are
lower power, but COM7 is going away at the end of the month.

On Tue 07/06/2022 09:28, Brian Gaff wrote:
> Here line of sight to Crystal Palace, I normally get very good tv reception
> with a wide band loft aerial. I fear it might well be time, once again to
> change its coax or get a decent aerial fro Freeview. T multiplex which has
> channels 20 21 and some others on it is coming up no signal all of a
> sudden, unlike the others. Is this one particularly weak or very high in the
> band at this site. Its been fine for years, so unless its on reduced power,
> I guess its more expense. sigh.
> Brian
>
> PS I just tried the discone from my radio scanner on the TV, and get all
> the channels no problems, so I guess that is rather an obvious pointer that
> I have an aerial with built in attenuator all of a sudden. Last time it
> looked like something had eaten the pvc out of the coax. What is the best
> stuff these days? Maybe one that wildlife won't eat?
> grin
>
If you are L O S to X P it is possible the issue is excess signal, not
too little, plus - as a radio amateur you should know - we are at the
time of year when we get many and various lift conditions that can cause
all manner of problems. I would suggest Toolstation item 86843 which is
a 0-20dB R F attenuator with F-type connectors.

I'm not convinced its overload or lift conditions this time, It definitely
says no signal. But I'll test it tonight again. Last time water had got into
the coax. No sign of it on the bottom as you can often find if its got in.
What is the most durable cable these days.
Brian

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"Woody" <harrogate3@ntlworld.com> wrote in message
news:t7nhfo$2di$1@dont-email.me...
> On Tue 07/06/2022 09:28, Brian Gaff wrote:
>> Here line of sight to Crystal Palace, I normally get very good tv
>> reception
>> with a wide band loft aerial. I fear it might well be time, once again to
>> change its coax or get a decent aerial fro Freeview. T multiplex which
>> has
>> channels 20 21 and some others on it is coming up no signal all of a
>> sudden, unlike the others. Is this one particularly weak or very high in
>> the
>> band at this site. Its been fine for years, so unless its on reduced
>> power,
>> I guess its more expense. sigh.
>> Brian
>>
>> PS I just tried the discone from my radio scanner on the TV, and get all
>> the channels no problems, so I guess that is rather an obvious pointer
>> that
>> I have an aerial with built in attenuator all of a sudden. Last time it
>> looked like something had eaten the pvc out of the coax. What is the best
>> stuff these days? Maybe one that wildlife won't eat?
>> grin
>>
> If you are L O S to X P it is possible the issue is excess signal, not too
> little, plus - as a radio amateur you should know - we are at the time of
> year when we get many and various lift conditions that can cause all
> manner of problems. I would suggest Toolstation item 86843 which is a
> 0-20dB R F attenuator with F-type connectors.

On 07/06/2022 18:32, Brian Gaff wrote:
> I'm not convinced its overload or lift conditions this time, It definitely
> says no signal.
But how does it determine there's a signal ?  Usually for digital
receivers if they can 'see' a valid COFDM signal.

Point a DVB-T only receiver at a DVB-T2 mux, and it will also say 'no
signal'

Well its working again last night. I wonder if it was on low power for some
reason the day before? I'm still very suspicious that its not working well,
since the discone experiment. I mean its not even tuned to the band, its
broadband by its nature, and not very polarised either.
Brian

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"Mark Carver" <mark.carver@invalid.invalid> wrote in message
news:jg9iqsFpnq7U1@mid.individual.net...
> On 07/06/2022 18:32, Brian Gaff wrote:
>> I'm not convinced its overload or lift conditions this time, It
>> definitely
>> says no signal.
> But how does it determine there's a signal ? Usually for digital receivers
> if they can 'see' a valid COFDM signal.
>
> Point a DVB-T only receiver at a DVB-T2 mux, and it will also say 'no
> signal'